1. Field of the Invention
This invention is in the field of paving compositions comprising the jellied product formed by reacting asphalt and rubber, and which is the subject of applicant's U.S. Pat. Nos. 3,844,668, 3,891,585, and pending United States application Ser. Nos. 622,143, filed Oct. 14, 1975 now U.S. Pat. No. 4,021,303, and 584,478, filed on June 6, 1975 now U.S. Pat. No. 4,018,730.
2. Description of the Prior Art
Paving compositions manufactured by reacting asphalt and rubber are significant improvements over prior paving materials, and constitute a new use for hitherto unwanted scrap rubber, such as old tires. In manufacturing these compositions, the asphalt and rubber are mixed and heated to a temperature range between about 350.degree. to about 500.degree. F until the desired reaction takes place. While the asphalt-rubber mixture is heated to the desired reaction range, the viscosity of the mixture continues to decrease as the temperature increases until the reaction temperature range is reached whereupon the viscosity increases as the reaction temperature increases.
Equipment designed for handling and applying paving material, such as by spraying, requires that the viscosities of the paving material not exceed 3,500 to 4,000 centipoise. The viscosity of the asphalt-rubber reaction product is generally much greater than that, and must be reduced by admixing diluents, such as kerosene, by using a relatively coarse rubber, by regulating the ratio of rubber to asphalt, or by using a less viscous grade of asphalt.